Along with the recent development of network technique and accompanying digital implementation of book data, music data and so on, a technique of distributing data using a communication network has been developed. Examples of such a technique are disclosed, for example, in Japanese Patent Laying-Open No. 2-47771 and Japanese Patent Publication No. 5-83948. The inventions disclosed in these published documents relate to a technique for down-loading electronic book data to a storage device such as a memory or a hard disk through a communication network and not through a bookstore, and reproducing the data by a reproducing apparatus.
More specifically, Japanese Patent Laying-Open No. 2-47771 discloses an information transmitting system including a data supplying apparatus and a data reproducing apparatus connected thereto by a communication network. The data reproducing apparatus instructs the data supplying apparatus on the data to be retrieved, through the communication network. The data supplying apparatus includes a data base storing a number of data groups, a searching apparatus searching any of the data groups in the data base in accordance with the instructions from the reproducing apparatus, and a communication apparatus for data transmission/reception to and from the data reproducing apparatus.
The data supplying apparatus structured in this manner retrieves the data group instructed by the data reproducing apparatus from the data base, in response to a request from the data reproducing apparatus and transmits the data group through the communication apparatus and the communication network to the data reproducing apparatus. The data reproducing apparatus has a storage device storing the data group, and displays page by page the data group stored in the storage device, based on an instruction from the user. Thus it is possible for the user to obtain data of a book and the like simply through the communication network, without any intervenient bookstore. It is possible for the user to reproduce the data at any time and at any place as needed, using the data reproducing apparatus.
Japanese Patent Publication No. 5-83948 discloses a public information vending system including one or a plurality of public information vending machines installed at places readily accessible by unspecified number of information purchasers, and one or a plurality of information source apparatuses connected to the public information vending machines through a communication network. In this system, the information purchaser connects to any of the information source apparatuses that contains information of which purchasing is desired through the public information vending machine and the communication network, and makes a transaction for purchasing the desired information. Confirmation of an identification ensuring adjustment or payment of charges takes place at the time of completion of the transaction contract at the public information vending machine. At the same time, the purchaser can obtain immediately the desired information from appropriate information source apparatus through the public information vending machine and the communication network. It is expected that such a system promotes distribution of information.
In such a transaction, the information is once recorded on a storage medium and reproduced by the reproducing apparatus. As the digital data allows easy copying of data and are free of any degradation of data in data reproduction, there arises a problem of how to prevent unauthorized copying of the storage medium. Conventionally, a method has been known as one such technique in which copying is restricted by a flag indicating prohibition or allowance of copying. In accordance with such a method, when a recording apparatus is connected to a reproducing apparatus and an attempt is made to copy the data reproduced by the reproducing apparatus on a storage medium by the recording apparatus, the recording apparatus checks the flag embedded in the data. If the flag has a value that means copy-prohibited, the recording apparatus prohibits copying, or provides analog outputs instead of digital outputs, so as to prevent digital copying.
SCMS (Serial Copy Management System) employed for a DAT (Digital Audio Tape) has been known as a representative example of such technique. In SCMS, a copy flag of 2 bits is recorded in multiplexed manner in the data at every prescribed time period, so as to prevent unlimited digital copying. The copy flag has the definitions of “00: copy prohibited”, “01: one copy allowed”, “10: reserved” and “11: copy allowed,” and copying is controlled by an appropriate operation in accordance with the copy flag.
The conventional technique outlined above is very convenient for distributing electronic data to the users. Actual use of such technique, however, has the following problems.
(1) When the capacity of the data to be distributed increases, necessary time for transmission becomes longer, resulting in excessively long wait time of the user. When the object of electronic distribution is extended to publications including a large number of photographs and/or pictures such as a picture book or a photograph album or further to CD (Compact Disk) albums having larger capacities than the text data, such an excessive wait time imposes a great difficulty in spreading the system. The time necessary for the user to obtain a desired book or the like through the common sales route, for example, at a bookstore, is generally unrelated to the contents of the publication. Therefore, solution of this problem is critically important if the system for distributing electronic data through communication is to be practically implemented.
(2) The problem of copyright protection is very important in a simple system of data distribution. If protection of copying of digital data is not at all afforded, it is impossible to detect any unauthorized copy by a malicious user purchasing the electronic data. This is a major difference between a paper document which requires time for copying and the electronic data. Embedding a copy flag within the data, as described above, may be a solution to this problem. Nevertheless, unauthorized copying cannot be prevented if an apparatus which ignores the copy flag is used as the recording apparatus. In other words, practical implementation of such data distribution system requires technical support to solve not only the technical problems but also institutional constraints including copyright protection.
(3) Another problem of the conventional technique is that a situation where various data sources (information sources) utilizing different communication rates and different communication methods coexist is not taken into consideration. For example, computers of various generations may possibly be the data sources, and the speed of processing of the computers may vary widely. Storing capacities thereof may also differ widely. Further, the method and the rate of communication may vary widely, possibly including wired communication, wireless communication, communication through optical communication, satellite network or satellite broadcast allowing broadcast of same data to multiple points simultaneously. Therefore, when there are a plurality of data sources holding data desired by a user, it becomes a problem from which data source the data should be received. In such a case, it is desired that an optimal data source can be selected automatically based on various standards.
As such various and wide data sources were not expected conventionally, optimization of data source selection has not been considered.
(4) Conventionally, a so-called “browsing in a bookstore” has been possible. When one wishes to a buy a book, he/she may actually look into the contents before determining to buy or not to buy the book. Electronic distribution of data makes it difficult for the user to examine the contents of the data before the purchase. In the conventional technique described above, accounting of the purchase of the electronic data takes place at the time of purchase, that is, at a time point when the data is received from the data source. Therefore, there is a relatively high possibility for the user to find that the contents of the purchased electronic data is not so interesting as expected. Such a problem may hinder use of the data distribution system by the users.
Japanese Patent Publication No. 6-85196 discloses a software vending machine solving such a problem. The software vending machine has a function of demonstrating the software of the user at the time of purchasing the software. Such a demonstration of the product to be purchased, however, does not allow the user to filly appreciate the true value of the product, except for only a few software products. Similarly, since books generally require significant time to be fully appreciated, they also cannot be sufficiently evaluated by a user according to this method. This problem must be solved to spread the use of the electronic data distribution system.
(5) The conventional technique described above has a problem that what can be purchased is limited to data already in the electronic form. This seems to be a matter-of-fact constrict. Where it is known that wide variety of contents not in the electronic form are available through the traditional route as in the case of books, there would be only a small number of users who would be eager to use such an electronic data distribution system that allows access to information of very limited contents. Therefore, a system allowing purchase of data which may or may not be in the electronic form, in a single manner is desired.
(6) In the conventional technique, the unit of transaction has been, in principle, the whole data of an electronic book, for example. Now, there may be a method of utilizing data in which data source search is conducted by a key word, and a portion including the key word is retrieved. At this time, a user may wish to retrieve not the segments of sentences including the key words but a section, a chapter or other sizable unit from the data source. Conventionally, such an apparatus for retrieving data in such a form from the data source did not exist.
(7) As already described, there is a method of determining whether a copy is allowed or not, based on a value of a copy flag included in the data, when there is an instruction for copying the digital data. When the value of the copy flag is set to indicate “copy prohibited”, the user suffers from a problem that it is impossible to copy the data for back up. A back up copy is legitimate and hence there must be some measure for the user's convenience.
Therefore, an object of the present invention is to provide a data distribution system capable of reducing time necessary for data transfer as much as possible, and a data distributing apparatus and a data reproducing apparatus therefor.
Another object of the present invention is to provide a data distribution system effectively preventing unauthorized copying in electronic data distribution.
A still further object of the present invention is to provide a data distribution system capable of distributing data to the user from an optimal data source in accordance with various standards.
An additional object of the present invention is to provide a data distribution system allowing data purchase at a reasonable expense.
A further object of the present invention is to provide a data distribution system allowing a user to select any article other than electronic data.
A still further object of the present invention is to provide a data distribution system allowing distribution of data in a unit of utility value for the user.